Lens-grinder attachment



J. J. KOVACS LENS GRINDER ATTACHMENT Filed July il, 1920 2 IIIIIIEIIIVIVIIIq-V] -2l @Q INVENTOR.

BY MATTORNEYS Patented Apr. 24., 192?.

PATEEN Ti QfF-f f l ,msm-1n' a xovAcs','oF cannes, new' Jansen Lsnseamnna 'Mandarina'.

Te aitwwm t may concern.' Be it known thatI, JOSEPH J; Kovacs, a citizen of the' UnitedStates, residingin lthecity'of Orange, county of Essex, and

State of New Jersey, have invented a new and 'useful Improvement in 'LenseGrinder Attachments, of which the following isa Specification. y y

lnth'e grinding of llenses for spectacles, .itis the practice. to grind the faces of the v.lens for correct convexity or concavity, the

material being Voriginally in arough cir- `cularydisc form; ithereafter the lens is shaped roughly to form by breaking` oil 'the edge or margin, solas to givethe' partially nished. lensya geneialfi elliptical form; .iinallythe vlens iswplaced-in what is known inathe art asy a lens edge grinder, inwhich the edge Vof the lens isin ly ground to the l'exact shapev for `use asra spectacle lens. @In the machines now 1n general use, great care mustv be exercised in this edge lgrinding process.A The'lens with its unfinished edge,

is accurately inserted in arubber jawed,

lspring pressed lens chuck, and held with a yielding lpressure against the facev of a ro- -tating' grin dstone., Means are 1 also providedffor slowly rotating thef chuck-with the lens therein, andsuch chucklis guided .by a patternof exactly the final shape which the lens is `to take, but somewhat smaller. f In: grinding o'val'lenses it has been hitherto thel i practice tov hold `the lens `against the stonefby means of a coil contractile spring, one end of which is attached vto--some fixed partv ofL the grinding machine,

and the otherfend adjustably connectedto soine partofthe rockingfframell which carf forml-,of mechanism" resides inthe 'fact that o-vahfol .llip,tical-llens;V this "rocking ffra'me is, requiredto oscillate back andi forth to a distance equal vto tthefdiiference .between Ythe major and minor axes-Lof. the lens.' A'I his Koscillation results in placingthe contractile spring, above 'referred to, under greater tension as the major axis of the lens approaches contact-with the grindstone, and it ifrequently follows thatbecause of the resultant increased pressure the lens itself. lmay be broken,'or since it is-held by friction alone between the rubber faces ofthe lens holdingchucln'the lens itself is sometimes shifted wherein App1icanonn1ediu1y 1, 19202 seriaifNo. 393,294.

from itsfplace, if not completely forced out of thel chuck. Again, because of this unequal pressure upon thevedge of v'the elliptical lens the extremities of the major axis of the lens are more quickly ground'than the extremities of the minor axis, 'resulting in a longer time'required to vcomplete the edge grinding process. Moreover the 'process'as; justdescribed, requires the constant attention of an operative during thegrinding process lest the lens be broken or shifted from its place, and alsoyto properly'adjust the tensionv of the spring 'asv the grinding downV to final form gradually progresses;

-My present i improvement resides' in the substitution" for the" adjustable` spring mechanism'above described," ofa lever with an i. adjustable weight thereon, so that vno matter what part of th'eedge of the lens shall be in contact with the grindstone, the' pressure between the edge of the lens and the 'stone shallbe uniform. Furthermore, by the use of my Vimprovement I am able to materially shorten 'thetim'e required to fgrindzthe edge of a single lens. Ink some of the operative, by my improvement the operative is required only to' give his Eattention-to the proper setting vof thellen's inthe chuck, start. thel operation, and later when the grindingv is about half completedffreadjust-the weight upon the attachment, after which the grinding operations is completed without `furtlrier attentionlf'i'lhis"gives fthe 'operative anu o'pportu'nity:-vv to rattend" 'to five or six'i differentfgrinding macliinesat the same time, whereas under the-oldjfsystein a Ysingle operative wasrequiredto give hisentir'eiattention toa singlezmachine. .I haveV 'illustrated I the several 'steps of lens' edge grinding, andtalsoi my improvement in the. accompanying drawings,

'F ig. l, represents a roughly, circular'lens ldisc prior to rough shaping.

Fig. 2, illustrates the roughly shaped lens,

'Fig. 3, the completed lens.

Fig. 4, illustrates in part, so much of the usual grinding mechanism with my attachment secured thereto as is necessary to understand its use and operation.

Fig. 5, is a detached side view of my improved attachment showing the relative positions of the rocking chuck frame in dotted lines. r

Fig. 6, is an end elevation of my improved attachment.

Fig. 7, is also an end elevation but shows a slightly modified form of weight.

Fig. 8, is a modified form of the device for producing a uniform pressure of the lens upon the stone.

Similar reference numerals refer to like parts throughout the specification and drawings The lens disc 1, as above described, is of roughly circular shape, with its faces corectly ground for convexity or concavity. The pattern of the finished lens is laid upon the face of the disc 1, and the projecting edge of the disc is broken away roughly down to the form illustrated in Fig. 2, at 2. In this form the roughly finished lens 2, is plmed between the chucks '3, and 4, of the lens grinding machine. These rubber faced chucks are mounted respectively upon the spindles 5 6, the later being longitudinally slidable in the bearings '7, against a coil spring 8, said spring being utilized for forcing the spindle 6, and the chuck B, with elastic pressure against one of the faces of the lens 2. The chuck frame 9, is mounted upon a shaft 10, which runs longitudinally therethrough, said shaft being mounted in journal bearings 11, upon the table of the machine. Near the ends of the shaft 10, just inside of the bearings 11, are the two pinrions 12-13, which are respectively in engagement with the gear wheels 14 and 15, the latter beingT respectively mounted upon the chuck spindles 5 and 6. It will be noted thatthe pinion 13, is a double faced pinion to provide for thelongitudinal shifting of the gear wheel 15, when the spindle 6 is shifted to open the chucks 3 and 4. The shaft 10, has a large gear wheelv 16. by which it is driven. The grindstone 1'4", is mounted upon the shaft 20. carried in the bearings 18-19, and is driven by any external source of power.

It will be noted that the frame 9, being mounted upon the shaft 10, is free to oscillate within certain limits so as to carry the edge of the lensv2, against the face of the stone 17.

rThe structure thus far described is well known in the art, and its operation is common practice. As above noted, it is common practice to connect the upper part of the frame 9, as for example one of he bearings 7. by means of a coil spring to one of the bearings 18, or 19, so as to give the requisite pressure of the edge of the lens 2, against the face of the stone 17. As above described, the rotation of the lens against the stone is attended by the oscillation of the frame 9, upon the shaft 10, as the major and minor axes of the lens pass into contact with the face of the stone. This results in the placing of the coil spring, above described, under greater or less tension, with a consequent varying pressure upon the stone.

My present improvement consists in entirely dispensing with this connection and substituting therefora 4weight arm 21, having a strap connection 22, for fastening the same to one of the chuck spindle bearings 7 with the arm 21, projecting forward toward the driving shaft 20. The strap connection 22, surrounds a portion of the bearing 7, and is rigidly fixed in place by means of the bolt 23, and nut 24. The arm 21, carries a wei htl 25, suspended therefrom and adjusta le therealong. If desired the face of the arm 21, may be provided with a scale, as 26, so that the pressure due to the weight 25, upon the arm 21, may be accurately determined.

I have shown in Fig. 5, a large dotted oval 2T. representing an elliptical lens, its major axis vertical and its minor axis horizontal. lVithin such large dotted lined oval, I also show ya smaller dotted line oval 28. which represents the pattern, or exact final shape which the finished lens is to take. This pattern is shown in Fig. 4, in edge view at 28, as bearing upon the adjustable gauge 29, and its purpose is to limit the grinding of the edge of the lens tothe exact shape of the pattern 28. This, however, is old in the art and forms no part of my invention.

It will be noted that with my improved attachment, the pressure between the lens 2, and the stone 17, under the influence of the weighted arm 21. is at all times the same, thereby preventing unequal grinding of the edge of the lens and thereby preventing breakage, or the forcing of the lens itself from its accurately adjusted position between the rubber faced chucks 3 and 4.

In Fig. 8. I have shown a slightly modified form of. my improvement which accomplishes the same purpose. In this form I providethe machine table with a bracket 81; upon its rear side said bracket having a groovedv roller at its upper extremity. Passing over this roller is a cable or c hain 30, connected at its forward end b v means of the hook 29', to the chuck frame 9. At the opposite end of the chain or cable 30, and suspended therefrom is a series of weights 32. It is obvious that the strain upon the chain or cable 30, due 'to the suspended weights 32, will maintain a uniform pressure of the edge of the lens 2T. against the face of the stone 17. Should it be desired to increase this pressure more weights 32, could be added` and likewise if less pressure were required some of the Weights 32, could be removed from the chain or cable 30.

By the use of my improvement I am able to .accomplish the following results:

First :'a more rapid grinding of each individual lens.

Second: reduction of breakage of lenses die to non-uniform pressure upon their e es.

lhird: the shifting of the lens in the lens chuck is entirely obviated.

Fourth: thev operative is relieved from constant attention to the machine during the grinding operation, so that he may be able to handle and keep in operation several machines simultaneously.

Fifth: a material reduction in the cost of lens making.

I claim:

An attachment for lens edge grinders comprising an arm having clamping means at one end thereof for rigidly but adj ustably securing said arm in horizontal relation to the rocking frame of the lens grinder, and a Weight adjustably suspended from said arm whereby the edge of a lens held upon said rocking frame may be caused to bear with uniform yielding pressure upon a grindstone during a complete revolution of said lens.

JOSEPH J. KOVACS. 

